inspecting under the hood

Are Isuzu engines reliable?

Isuzu is a brand known for its diesel engines as well as tough pickups, versatile SUVs, and reliable trucks. The said products enabled this Japanese automaker to be one of the most popular car brands globally. It stood the test of time by believing in what it wants to achieve and by constantly finding ways to innovate its strengths, which are the diesel as mentioned above engines, pickups, SUVs, and trucks. The Japanese automaker launched its new RZ4E Blue Power diesel engine in 2015 in Thailand, which is said to deliver improved fuel economy and cleaner exhaust emission. The said engine was first introduced in the Philippines last March 2018, and it is now equipped in the 2018 D-Max, mu-X, and its truck fleet. With that, here is the story of how Isuzu began its journey into becoming a global brand.

Isuzu engines are engineered to produce an understated power and torque output to create a de-stressed environment, therefore reducing engine wear and promoting component longevity. The reliability is determined by creating the optimum fuel/air mixture and ensuring that the heat generated by the combustion process is constant and also dissipated uniformly.

Isuzu engine design efforts are aimed at generating maximum torque at low engine speeds—under 2000 rpm—because at those speeds fuel consumption is at its most economical and the engine’s response characteristics are perceived as positive; i.e., it has good ‘pulling power’.

What’s involved in the development of a new engine?

Diesel engine development is a constant evolution, so it’s impossible to put a single time frame on any particular engine. That said, the latest generation of the 4JJ1 diesel engine that powers the D-MAX and MU-X was rigorously tested over approximately four million kilometres! Isuzu is working tirelessly to improve its diesel engines further to produce higher output and durability while maintaining class-leading thermal efficiency among 3-litre diesel engines. At the same time, the company is pouring its energies into a clean diesel engine R&D with the aim of reducing emissions of particulate matter (PM) and nitrogen oxides (NOx).

Isuzu understands what commercial customers demand from a work vehicle: value for money driven by a low total cost of ownership, and reliability that you can depend on to keep the job going.

Geared towards reliability, durability and economic benefit, the 21 D-MAX utes and six MU-X SUV variants within the Isuzu UTE range are equipped to handle all aspects of your business. They are all driven by an exclusive Australian powertrain consisting of the legendary Isuzu three-litre turbo diesel engine, and a six-speed automatic or manual transmission.

Revered as the benchmark of light-commercial diesel engines, the newly-refined 4JJ1 three-litre engine – available in all D-MAX and MU-X vehicles – produces 130kW of power and 430Nm of torque at a low 2000rpm. This advanced Euro5-compliant engine delivers consistent levels of torque throughout the rev-range, ensuring improved drivability, effortless towing of up to 3.5 tonnes and improved load carrying performance.

Isuzu engines are well-known for their durability and real-world fuel efficiency. Encompassing over a century of diesel engine development, the D-MAX and MU-X’s highly refined turbo-diesel engine offers superior fuel efficiency, courtesy of newly-designed engine internals, refined fuel injection system and a new turbocharger which feeds air through an efficient large front-mounted intercooler.

Is it true that manufacturers have only one engine control unit map that caters to all countries and all fuel qualities, or are vehicles delivered to specific regions or countries with differing programming?

No—countries have different emission standards, and so Isuzu has differing standards to comply with the local regulations and to help assist with inferior fuel qualities found in some countries or regions around the world.

What steps has Isuzu taken to ensure the reliability of its engines/fuel systems/turbos that other manufacturers might not?

The 4JJ1 has a scissor gear (split design) camshaft drive gear, which eliminates backlash on deceleration and results in reduced wear. Our engines’ connecting rods have large big-end bearings, making them stronger and therefore last longer. And we use robust cast roller rocker arms with larger roller bearings, plus roller pivot bearings, reducing friction and making them longer wearing—some manufacturers use pressed metal roller rockers with small roller bearings and no pivot bearings. In contrast, other manufacturers use no rockers at all.

Are some components in a CRD engine worked harder than if it was a traditional mechanically injected diesel?

Yes—to begin with, the fuel system has to deal with 26,000psi injection pressure! The resulting combustion process subjects the pistons, connecting rods and crankshaft to significant dynamic forces due to the more efficient combustion.

Fuel contamination is said to be one of the biggest killers of a common-rail engine due to the fine tolerances in the injection system. How far do manufacturers go to refine the filtration system and ensure it’s up to the task? For example, is it designed to cope with a certain amount of contaminants such as water or dirt, and are there fail-safes? Or is damage due to fuel contamination simply unavoidable?

The use of poor quality fuel will have a negative effect on a CRD fuel system— regardless of the manufacturer. The fuel filter and water separator are unable to remove all traces of water, especially once the fuel and water mixture becomes emulsified. Isuzu built its engine to be as durable as possible against such damage. First, by adopting a fuel filter that has the class-leading filtration efficiency and the function to separate the water. Secondly, with a filter that has a built-in, water-level-sensor-based alarm system. Moreover, the fuel injector is arranged to be durable with a special coating made for the interior parts, which protects against foreign substances.

If an owner modifies their engine, will it void their engine warranty?

Simply put, yes. Manufacturers have no data to support what, if any, impact such modifications will have on an engine. Isuzu spends considerable resources to ensure our engines provide optimum power and performance, as well as producing the best possible fuel economy, while still meeting the necessary emission regulations.

Many diesel chip suppliers claim their chip “will not void your warranty” because it doesn’t override the engine’s factory safety parameters. Is this true?

No—it is not driven by a “factory safety parameter”. Any modification of the engine control and emission components would be an infringement of most manufacturers’ warranty conditions, and therefore such practice is not recommended.

There are two industry standards for measuring engine life. These are called B10 and B50. Each uses statistical methods to estimate engine life. They are not generally quoted for light-duty vehicles, but that doesn’t mean they can’t be quoted.

Many people think the B10 standard means the point at which 10 per cent wear will take place, and the B50 standard is the point at which 50 per cent of wear occurs. This is not the case at all.

The B50 standard relates to the analysis of when (in the distance) 50 per cent of engines will require major repairs, an overhaul, or replacement. B10 is the same thing, only the point when these repairs/replacements are required on 10 per cent of engines.

Major repairs or overhaul means any repair that requires removal of the cylinder heads and/or oil pan.

The standard is a statistical, standardised analysis which is good for comparison purposes – but it’s not a guarantee of how long your particular engine will last. That depends significantly on operational factors.

In the quote above, Isuzu has ‘sexed up’ the language of the B10 standard, by putting a more positive spin on it. Instead of saying 10 per cent of engines will require a rebuild or major repairs by 500,000km the company has stated instead that 90 per cent won’t require major repairs/replacement by that distance.

I’m sure the diesel in the Isuzu will be quite durable. Isuzu is a good engine builder – no doubt about that, and this one is artificially limited to low outputs. Also, diesels generally are longer-lived than petrols. This is largely due to the fact that the lower RPMs impose lower stress on the moving parts and hence wear rates drop.

As to relevance, most longevity claims, however accurate and standardised, are irrelevant to most new vehicle buyers. Most buyers turn the vehicles over in the 3-5 year term and are generally well under 100,000km when re-sold. So longevity is a largely ‘Who cares?’ A deal for most buyers – in practice. (Although the idea you’re buying a power train that lasts a long time is nice, and it’s implied the fundamental engineering is robust to accomplish that – so there’s an implied link to reliability.)

Some people do own their new vehicles for donkey’s years, so longevity directly affects these owners. Longevity is, however, probably more of a concern for used-vehicle buyers.

It’s worth noting that engines seldom achieve the peak output figures – the peak power only ever outputs with wide-open throttle (meaning, in a diesel: maximum fuel delivery) and only then at those revs and against a balancing load. That’s hard to achieve without putting the vehicle on a dynamometer—likewise peak torque – only at those revs and at wide-open throttle.

So in practice, most driving is done at a fraction of those outputs. As soon as the driver backs off the throttle, less fuel is delivered, and therefore less torque is delivered at the crankshaft.

The biggest contributors to wear from a user’s perspective are the number of cold starts and servicing. If you want the engine to last forever, never let it cool down (which is why taxis routinely the last 750,000km). The metal expands when it warms up. This means the critical clearances between the parts, which the oil film covers, is only exactly right at normal operating temperatures. Therefore, most wear takes place when the engine is warming up. Many short trips (10km to the office, shut down for 8 hours, 10km home, shut down overnight) will wear the engine out at a much shorter distance than 500km a day over the course of a working day.

Conservative driving during the engine’s warm-up phase will help reduce wear while the parts are getting their tolerances right. Conservative driving generally imposes less stress on drive trains because the engine generates lower outputs. At the other end of the spectrum – in racing, where engines operate at or near peak outputs much more regularly – longevity is the first casualty. Rebuilds are frequent. The funny thing there is: there’s not a linear relationship between how hard you drive and the powertrain life: driving like Nanna won’t get you much more longevity than driving normally and conservatively, but driving all the time like a Type A driver with rabies will slash longevity. And racing will kill the vehicle even quicker.

Also, oil degrades with time, so changing oil and filter every 10,000km or three months would aid longevity even though the manual generally says six months or 15,000km.

Driveability and fuel economy is further enhanced throughout the range with the addition of a new advanced six-speed automatic transmission with sequential sports mode. The automatic transmission also features an adaptive-learning function which constantly monitors brake and throttle applications. This allows the transmission to select the most appropriate gear shift and lock-up instinctively, points depending on the driver’s input, as well as the vehicle’s load and speed. A smooth and intuitive shift six-speed manual transmission is also available.

Don’t just take our word for it though. The Isuzu UTE range recently won the 2018 Car Manufacturer of the Year award and the Best of the Best Customer Satisfaction award at the 2018 Roy Morgan Customer Satisfaction Awards.

Completing a great value proposition, a comprehensive care package backs all Isuzu vehicles, Service Plus 6-6-7 — offering a six-year warranty, six years Roadside Assistance and seven years Capped Price Servicing — for the ultimate peace of mind.

The final point I’d make is about press fluff generally – almost everything in a press release is overstated, even if factually correct. Isuzu might say something about delivering peak torque across a wide range of 1800-2800rpm. Still, the fact is: that limitation is artificial – imposed by the engine control software because part of the driveline was not able to withstand a greater output reliably. (Isuzu nutters hate it when I suggest this.)

It’s up to journos to interpret press releases, but unfortunately few of them have much technical appreciation.

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